A simulator is a device that enables an operator to reproduce or represent under test conditions phenomena likely to occur in actual performance. An example of the simulators is a virtual reality seat used for a cockpit model for training a driver of a car.
FIG. 1 illustrates a schematic view of a prior art simulator and FIG. 2 is a plan view of the simulator depicted in FIG. 1. The prior art simulator is provided with a base plate 100, a platform 200, and six actuators 300, the base plate 100 and the platform 200 being mechanically connected to each other through the actuators 300.
Each of the actuators 300, as shown in FIG. 3, is provided with a hydraulic cylinder 310, a sensor 320, a servo valve 330 and a pair of universal joints 350. The hydraulic cylinder 310 has a cylinder 311 and a plunger 312. The sensor 320 for sensing variation of length of the hydraulic cylinder 310 includes a sensor body 321 and a sensor rod 322 mounted on the cylinder 311 and the plunger 312, respectively. The universal joints 350 are mounted on the top and the bottom ends of the hydraulic cylinder 310, respectively.
A piston 313 is connected to one end of the plunger 312 which is inserted into the cylinder 311, dividing the inner space of the cylinder 311 into two parts. The upper part of the cylinder 311 is communicated with the lower part thereof through a pipe 314 and the servo valve 330. The servo valve 330 is connected with an inflow pipe 315 and an outflow pipe 316 for inflowing and outflowing a high pressure fluid, respectively.
When the high pressure fluid is flown into the hydraulic cylinder 310 through the inflow pipe 315, the servo valve 330 selectively passes the high pressure fluid to the upper part or lower part of the cylinder 311 to thereby vary the length of the hydraulic cylinder 310. At this time, the fluid is flown to the outer space of the hydraulic cylinder 310 through the outflow pipe 316.
The universal joints 350 help the actuator 300 to connect and support the base plate 100 and the platform 200 irrespective of the length of the hydraulic cylinder 310. Further, each of the universal joints 350 has a three degrees of freedom, allowing the platform 200 to have six degrees of freedom.
The operation of the prior art simulator is as follows:
When an operational signal is inputted into a controller(not shown), the controller generates and outputs a corresponding servo valve controlling signal to each of the servo valves 330 to control the length of the actuators 300. The sensors 320 sense and input the variations of length of the actuators 300 back to the controller. This process is repeated until an appropriate response to the operational signal obtained.
However, in the prior art simulator, when the platform is inclined by the respective variation of length of each of the actuators, resulting in each of the actuators having different length, a greater load is imposed on shorter actuators than on longer actuators. In order to accommodate this situation, each of the actuators are designed and manufactured to have a larger tolerance than necessary, increasing the manufacturing cost thereof.